JP3624307B2 - Crushing classification method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pulverization classification method and apparatus for pulverizing limestone, cement raw material, cement clinker, ore, silica stone and the like with a vertical roller mill and then classifying with an air classifier.
[0002]
[Prior art]
A pulverizing and classifying device for limestone, cement raw material, cement clinker, ore, silica stone, etc. (hereinafter referred to as pulverized raw material) is provided in a vertical roller mill pulverizing chamber provided in the lower part of the outer sealed casing, and in the upper part of the outer sealed casing. An air classifying chamber, a nozzle for supplying a primary air flow for conveying classification into the outer sealed casing to form a conveying swirl flow from the pulverizing chamber toward the classifying chamber, and a feeding means for supplying the pulverized raw material to the pulverizing chamber And.
[0003]
In this apparatus, the pulverized raw material is supplied to the vertical roller mill pulverization chamber via the feeding means and pulverized, and the pulverized raw material is directed from the pulverization chamber formed in the outer sealed casing to the air classification chamber. Ascends in the conveying swirl.
The raw material conveyed to the air classification chamber is classified into coarse powder (fine powder) and fine powder by an air classifier, and the coarse powder (fine powder) is returned to the grinding chamber and re-ground. In addition, the fine powder is separated from air through a bag filter and then collected as a product.
[0004]
[Problems to be solved by the invention]
When the pulverized raw material is pulverized and classified, the requirements for the size of the particle size and the width of the particle size distribution differ depending on the product to be manufactured.
Therefore, in order to obtain a product particle size distribution that meets the requirements, in the conventional example, a control method combining the following (1) to (3) or a control method combining (1) to (4) is used. Yes.
[0005]
(1) Change the inclination angle of the guide vane of the air classifier.
(2) Change the rotational speed of the rotor blade of the air classifier.
(3) Changing the classification air volume, that is, changing the primary airflow of the conveyance classification guided from the crusher inlet.
(4) Changing the interval between the grinding chamber and the classification chamber, that is, changing the height of the classification chamber.
[0006]
The control method of (4) includes a casing having different heights between the pulverization chamber and the classification chamber, that is, a casing for high side for classifying and adjusting fine powder, or a low side for classifying and adjusting coarse powder. The casing must be removed.
Therefore, this method is troublesome and goes against labor saving and improvement of the operation rate. Therefore, in reality, the above-mentioned control methods (1) to (3) are mainly used at the same time, and various particle size distributions are obtained by combinations of three manipulated variables.
[0007]
In addition, among the pulverized products pulverized in the pulverizing chamber, especially the lumps and flake lumps are operated under pulverization conditions such that they are not fallen out by the nozzle from the viewpoint of pulverization efficiency. . Therefore, when flakes are generated by pulverization in the pulverization region, the system cannot perform further pulverization.
[0008]
[Problems to be solved by the invention]
As for the particle size distribution of recent functional material powders, various distributions are desired as compared with the conventional particle size distribution. That is, on the sharp or broad distribution, there is a demand for a granular material in which coarse particles do not enter as much as possible, or a granular material in which the particle size distribution width is greatly different even with the same specific surface area.
In addition, from the viewpoint of labor saving, energy saving, and improvement of operation rate, easy operation is required for controlling the product particle size distribution.
However, in the conventional example, it was actually impossible to meet this requirement.
[0009]
In the fine pulverization region of the conventional example, the cohesive force of the fine powder becomes very strong, and aggregates (flakes) are generated in the pulverization chamber. Therefore, at the same time as the pulverization efficiency is significantly reduced, flakes fall against the primary airflow for transport classification and are discharged to the outside of the pulverization chamber, and the pulverizer cannot be continuously operated stably. Can no longer be performed, reaching the crushing limit.
[0010]
In view of the above circumstances, an object of the present invention is to make it possible to arbitrarily change the particle size distribution and to make the change simple and easy.
Another object is to improve the grinding efficiency in the fine grinding region.
[0011]
The present invention includes a vertical roller mill crushing chamber provided at a lower portion of an outer sealed casing, an air classification chamber provided at an upper portion of the outer sealed casing, and a primary air flow for conveyance classification in the outer sealed casing. A pulverizing and classifying device comprising a nozzle for forming a swirling flow from the pulverizing chamber toward the classifying chamber, and a feeding means for supplying a pulverized raw material to the pulverizing chamber; Crushing and circulating conveyance for crushing flakes discharged from the vertical roller mill crushing chamber and feeding them to the feeding means Means are provided.
[0012]
The present invention includes a vertical roller mill crushing chamber provided at a lower portion of an outer sealed casing, an air classification chamber provided at an upper portion of the outer sealed casing, and a primary air flow for conveyance classification in the outer sealed casing. A pulverizing and classifying device comprising a nozzle for forming a swirling flow from the pulverizing chamber toward the classifying chamber, and a feeding means for supplying a pulverized raw material to the pulverizing chamber; A particle size distribution adjusting means disposed between an upper end level of the pulverizing roller of the pulverizing chamber and a lower true lower end surface level of the classifying chamber, and introducing a secondary air stream for conveying classification into the conveying swirl flow; Crushing circulation conveying means for crushing flakes discharged from the vertical roller mill crushing chamber and feeding the flakes to the feeding means When, Is provided.
[0013]
This invention of Particle size distribution adjustment means Equipped with a flow rate control device It is characterized by.
[0014]
This invention The particle size distribution adjusting means includes a secondary air flow introduction section, and the crushing circulation conveying means is connected to the feeding means via a switching chute, and the switching chute is connected to the secondary air flow introduction section. Connected It is characterized by that.
[0015]
The present invention includes a step of supplying a pulverized raw material to a vertical roller mill pulverization chamber provided at a lower portion of an outer sealed casing, and pulverizing the pulverized raw material in the outer sealed casing, and air from the pulverization chamber. A pulverizing and classifying method comprising: a step of carrying a carrier swirl flow toward a classification chamber; and a step of air classification of the raw material conveyed to the air classification chamber;
The flakes discharged from the vertical roller mill crushing chamber are crushed and then returned to the crushing chamber via a feeding means for supplying a pulverized raw material.
[0016]
The present invention includes a step of supplying a pulverized raw material to a vertical roller mill pulverization chamber provided at a lower portion of an outer sealed casing, and pulverizing the pulverized raw material in the outer sealed casing, and the pulverization chamber A pulverizing and classifying method, comprising: a step of carrying a conveying swirl flow from the air toward the air classification chamber; and a step of air classifying the raw material conveyed to the air classification chamber; A secondary air stream for transport classification is introduced from the tangential direction in the transport swirl flow located between the upper end level of the classification chamber and the lower bottom end face level of the classification chamber, and flakes discharged from the vertical roller mill grinding chamber After crushing The pulverized material is returned to the pulverizing chamber through a feeding means for supplying the pulverized raw material.
[0017]
The present invention includes a step of supplying a pulverized raw material to a vertical roller mill pulverization chamber provided at a lower portion of an outer sealed casing, and pulverizing the pulverized raw material in the outer sealed casing, and the pulverization chamber A pulverizing and classifying method, comprising: a step of carrying a carrier swirl flow toward the air classification chamber; and a step of air classifying the raw material conveyed to the air classification chamber; Introducing a secondary air stream for transport classification from the tangential direction during the transport swirl flow located between the upper end level of the pulverization roller of the pulverization chamber and the lower right bottom surface level of the classification chamber; After crushing flakes discharged from the vertical roller mill crushing chamber, The crushed material is supplied to the introduction part of the secondary airflow for transport classification. It is characterized by that.
[0018]
This invention of Secondary airflow for transport classification The amount of introduction is adjustable It is characterized by that.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The present inventor supplies the secondary airflow for transport classification in the tangential direction to the primary airflow for transfer classification (swirl flow) rising from the crushing chamber toward the classification chamber in the outer sealed casing, and the flow ratio of both airflows is set. Various experiments were conducted on the assumption that the particle size distribution of the pulverized product could be changed by changing.
[0020]
As a result, it was found that the particle size distribution can be significantly changed by introducing the secondary air flow from the level between the upper end surface of the pulverizing roller in the pulverizing chamber and the level of the lower true bottom surface of the classifying chamber, and changing the flow ratio of both air flows.
[0021]
Further, flakes generated in the pulverization chamber are discharged from the pulverization chamber and returned to the pulverization chamber via the feeding means, or re-pulverized, or flakes discharged from the pulverization chamber are crushed by the pulverizing means and then fed. It has been found that the efficiency of pulverization is improved by returning to the pulverization chamber through means.
[0022]
Therefore, the present inventor has completed the present invention based on the above findings.
[0023]
【Example】
A first embodiment of the present invention will be described with reference to FIGS. In the pulverization classifier, a vertical roller mill pulverization chamber 3 is provided at the lower part of the outer sealed casing 1, and an air classification chamber 5 is provided at the upper part thereof.
[0024]
The crushing chamber 3 is provided between a crushing table 7 having a dam ring 6, a plurality of crushing rollers 8 disposed on the crushing table 7, and an outer peripheral portion of the table 7 and the casing 1. Nozzle 10 is provided.
[0025]
In the classification chamber 5, an air classifier 11 is provided. The air classifier 11 includes a plurality of guide vanes 13 and a plurality of rotor blades 20.
[0026]
The inner peripheral side end of each guide vane 13 is fixed to the lower end of the pin 15. The pin 15 is rotatably supported on the ceiling portion 14 of the outer sealed casing 1. Each pin 15 passes through the ceiling portion 14, and one end of an arm 16 is attached to the upper end thereof. The other end of the arm 16 is connected by a pin 18 to a long hole formed at an equal interval in the circumferential direction of the rotatable connecting ring 17. By rotating this connecting pin 18, all the guide vanes 13 can be tilted at the same tilt angle.
[0027]
The rotor blade 20 is disposed concentrically with the inner hopper 12, and a classification gap 22 is formed between the rotor blade 20 and the inner hopper 12. The rotor blade 20 is rotatably operated by remote control via an electric motor, a speed reducer, and a vertical axis drive (not shown).
[0028]
A fine powder outlet 30 is provided at the upper part of the inner hopper 12, and a coarse powder outlet 40 is provided at the lower part thereof.
The fine powder outlet 30 communicates with the exhaust fan 34 via the bag filter 32. The coarse powder outlet 40 communicates with a horizontal discharge facility 42 that penetrates the outer sealed casing 1.
[0029]
The outlet of the horizontal discharge facility 42 is connected to the inlet 43 a of the calibration device 43, and the outlet 43 b of the calibration device 43 is connected to the screw conveyor 51 via the circulation circuit 50.
[0030]
A mill feed bin 53 and a rotary feeder 54 are connected to the screw conveyor 51, and an outlet 51a thereof is connected to a screw conveyor 55 which is a raw material feeding means.
The outlet 55 a of the screw conveyor 55 faces the center of the crushing table 7. In addition to the screw conveyor 55, a chute, a belt conveyor, etc. can be used as a supply means. Further, the screw conveyor 51 can be omitted, and the mill feeder bin 53, the rotary feeder 54, and the like can be connected to the screw conveyor 55.
[0031]
The outer airtight casing 1 is provided with a secondary air flow introduction portion 60. As shown in FIG. 3, the introduction part 60 is composed of four introduction pipes 60P facing the tangential direction, and the number of the introduction pipes 60P is appropriately selected as necessary. The introduction portion 60 is provided at a position facing the lower portion of the coarse powder outlet 40 of the inner hopper 12, but is not necessarily limited to this position.
[0032]
According to the experiment, in order to be able to change the particle size distribution range greatly, it is disposed between the upper end level LL of the crushing roller 8 in the crushing chamber 3 and the lower end level (guide vane 13) of the classifying chamber 5 (the guide vane 13). Therefore, the secondary air flow introduction section 60 is disposed between the level LL and the level HL.
The introduction unit 60 is provided with control means such as a valve for adjusting the flow rate.
[0033]
Next, the operation of this embodiment will be described.
When the pulverizing and classifying device is driven, the primary airflow FA for transport classification passes through the damper 70 and the duct heater 71 and is ejected from the nozzle 10 of the primary airflow introduction portion of the pulverizing chamber 3 into the outer hermetic casing 1 and classified as a swirling flow. Head to room 5.
At this time, since the secondary airflow SA for conveyance classification is supplied from the secondary airflow introduction unit 60, the primary airflow FA rises while joining the secondary airflow SA, and passes through the guide vanes 13 to classify the air. It flows into the machine 11.
[0034]
The pulverized raw material M in the mill feed bin 53 is supplied to the screw conveyor 51 via the rotary feeder 54 and is sent to the screw conveyor 55 and falls from the outlet 55a of the screw conveyor 55 to the center of the pulverizing table 7 to be crushed roller. 8 to grind.
[0035]
The finely pulverized raw material BM rises while swirling on the primary airflow FA for transport classification swirling in the outer sealed casing 1, but in the vicinity of the secondary airflow introduction unit 60, the secondary airflow SA for transport classification. However, the raw material BM further rises on the mixed swirling flow W, passes through the guide vanes 13 and reaches the air classifier 11. Therefore, the raw material BM is classified twice during the ascending from the crushing chamber 3 to the classification chamber 5, that is, the primary air flow FA (air volume Q ₁ ) And mixed swirl flow W (air volume Q) of primary air flow FA and secondary air flow SA. ₁ + Q ₂ ) Classification and will receive.
That is, the raw material BM that rises while swirling on the primary airflow FA has coarse powder (A ₁ , A ₂ ), Fine powder (B ₁ , B ₂ ), Fine powder C is mixed, but the coarse powder A is larger (coarse powder A ₁ ) Falls below the swirl flow due to the primary air flow FA.
Next, large coarse powder A ₁ The raw material BM from which the slag has been separated rises due to the mixed swirl flow W. ₂ ) Is pushed by the wall surface of the outer sealed casing 1 under the influence of the centrifugal force due to the mixed swirling flow W, and drops upward while eliminating the ascending force.
[0036]
In this way, the raw material BM, which is obtained by separating the coarse powder A into the fine powder B and the fine powder C, flows into the classification gap 22 between the guide vane 13 and the rotor blade 20, and is subjected to a one-stage centrifugation by a swirling flow (free vortex). Undergoes separation. And among the fine powder B, a large one (fine powder B ₁ ) Are separated by the guide vane 13, and are separated from the flow of the carrier air and sequentially fall downward.
[0037]
And among the fine powder B, a small one (fine powder B ₂ ) And fine powder C flow into the vicinity of the rotor blade 20, and the fine powder B contained in the mixed airflow by the two-stage centrifugal separation action by the swirl flow (forced vortex) of the rotor blade 20. ₂ Is blown off toward the guide vane 13 and falls.
[0038]
These fine powders B (B ₁ , B ₂ ) Slides down the inner surface of the hopper 12, falls into the horizontal discharge facility 42 from the fine powder outlet 40, and is sent to the inlet 43 a of the calibration device 43 for calibration. After completion of the calibration, the fine powder B is sent from the outlet 43b to the circulation circuit 50 via the rotary feeder 54, returned to the screw conveyor 51 again, and sent to the grinding chamber 3 together with the grinding raw material M.
[0039]
The fine powder C on the fine powder side that has participated in the above-mentioned two-stage centrifugal separation flows between the blades of the rotor blade 20 while swirling, rides on the mixed airflow, and is sent from the fine powder outlet 30 to the bag filter 32. And separated. This fine powder C is accommodated in a container 81 on a platform scale 80 via a rotary valve 54.
[0040]
The above is the outline of the operation of this embodiment.
In this embodiment, the secondary airflow SA for conveyance classification is supplied into the outer closed casing 1 with a flow rate Q. ₂ By introducing and increasing the air flow rate, the flow rate Q of the primary air flow FA ₁ Concentration of powder to be classified (kg / m ³ ), The classification efficiency is surely improved and the flow rate Q ₁ And the flow rate Q ₂ Airflow ratio Q ₂ / Q ₁ The particle size distribution and powder concentration (kg / m) of the raw material BM introduced into the classification chamber 5 by changing the range from 0 to 1.5, for example, ³ ) Can be significantly adjusted as compared with the conventional example, and the particle size distribution width of the recovered fine powder can be controlled over a wide range.
[0041]
This airflow ratio Q ₂ / Q ₁ In addition to the above change operation, the particle size distribution width can be significantly changed even with the same specific surface area by adjusting the inclination angle of the guide vane 13, the rotational speed of the rotor blade 20, and the adjustment of the classification gap 22 between the guide vane 13 and the rotor blade 20. In addition, it is possible to remarkably prevent coarse particles from entering.
Furthermore, this air flow ratio Q ₂ / Q ₁ Since the change can be made only by controlling the flow rate control means, for example, a valve, the operation is very simple.
[0042]
A second embodiment of the present invention will be described with reference to FIG.
The difference between this embodiment and the first embodiment is that a flake extraction means 90 such as a rotary valve or a double damper is provided between the crushing chamber 3 and the circulation circuit 50, and flakes HF generated in the crushing chamber 3 are removed from the outdoor. And is sent to the screw conveyor 51 through a circulation circuit 50 such as a conveyor, and is sent again to the crushing chamber 3 together with the pulverized raw material M to be pulverized again.
[0043]
In this manner, the flake HF is returned to the crushing chamber 3 and repulverized by the crushing roller 8 to further extend the conventional fine crushing limit in the fine crushing region.
According to this example, for example, in the case of fine pulverization of charcoal cal (limestone), the product particle size distribution is 45,000 cm in terms of specific surface area (brane value) ² / G, so that the brain value of the conventional example is 27,000 cm. ² As compared with / g, the pulverization can be greatly achieved.
[0044]
A third embodiment of the present invention will be described with reference to FIG.
The difference between this embodiment and the first embodiment is generated in the grinding chamber 3 by providing a flake crusher 95 such as a pin mill, a novo rotor, a jet mill or the like between the grinding chamber 3 and the circulation circuit 50. The flake HF is crushed by the flake crusher 95, and the crushed flake HF is sent to the screw conveyor 51 through the circulation circuit 50 with the switching chute CS and again sent to the crushing chamber 3 together with the pulverized raw material M.
The crusher 95 and the circulation circuit 50 constitute a crushing / circulating conveyance means.
[0045]
The switching chute CS is also connected to the secondary air flow introduction unit 60. By operating the switching chute CS, the circulation circuit 50 and the introduction unit 60 are communicated with each other, and fine powder of crushed flakes is introduced into the introduction unit 60. To the secondary airflow SA, and circulated and conveyed to the classification chamber, and the coarse powder may be returned to the pulverization chamber and re-pulverized.
[0046]
In this way, the pulverization efficiency can be further promoted by crushing the flakes HF.
More specifically, it is possible to promote further fine pulverization in the fine powder region of the roller mill, and at the same time, crush and pulverize in the pulverization section as compared with the case where the flakes are directly returned to the pulverization chamber without being crushed. The bulk specific gravity of the object to be pulverized can be increased by making the pulverized powder suitable for various pulverized raw materials, and a continuous stable operation can be performed.
[0047]
In addition, the forced circulation by the cracking of the flakes eliminates the trouble of the flake treatment and can save labor and improve the operating rate.
Furthermore, since the vibration unique to the roller mill in the fine pulverization region is remarkably reduced, a high pressing force can be obtained by adjusting the pressing force of the pulverizing roller to an appropriate crushing powder degree according to various pulverized raw materials within the allowable vibration range. Can be arbitrarily set.
As a result, the fine pulverization efficiency is significantly improved, and it is possible to increase the amount of product produced at the time and to reduce the production power source unit (kwh / t).
[0048]
The control circuit used in this embodiment will be described with reference to FIG.
In FIG. 5, 100 is a mill supply amount control circuit that controls the mill supply amount, 101 is a classification air amount control circuit that performs constant value control of the classification air amount, 103 is a mill outlet temperature control circuit that performs constant value control of the mill outlet temperature, and 105 is A mill power control circuit that performs constant power control of the mill power, 107 is a roller pressure control circuit that adjusts the pressure applied to the roller, 108 is a pressure reduction alarm switch of the control circuit 107, and 110 is a mill differential pressure control circuit. Show.
[0049]
The mill supply amount is controlled by controlling the mill power (for example, electric power kw) of the vertical roller mill or the differential pressure (mmH) between the inlet and outlet of the mill body. ₂ The changeover switch 37 is operated so that O) becomes constant.
[0050]
The constant value control of the classified air volume is performed by automatically changing the opening degree of the motor damper 102 of the exhaust fan 34.
[0051]
The constant value control of the mill outlet temperature is performed by automatically changing the temperature of the duct heater 71 at the mill inlet.
[0052]
The constant power control of the mill power is performed by automatically changing the mill supply amount.
[0053]
A fourth embodiment of the present invention will be described with reference to FIG.
The difference between this embodiment and the third embodiment is that the horizontal discharge facility 42 is omitted and the coarse powder outlet 40 of the inner hopper 12 opens toward the grinding chamber 3.
Therefore, in this embodiment, the fine powder B classified by the air classifier 11 falls directly into the crushing chamber 3.
[0054]
An experimental example will be described.
In order to compare the pulverizing and classifying apparatus of the conventional example and the pulverizing and classifying apparatus of the present invention,
Classifier rotor blade rotation speed 3,000-5,000 rpm,
Vertical mill table rotation speed 50rpm,
Vertical mill roller pressure 3 tonf / 1 roller,
Exhaust fan air volume 25-50m ³ / Min,
Mill inlet damper opening 100% / Primary air flow FA volume Q ₁ 25-50m ³ / Min,
Secondary airflow SA intake damper opening 48-100% / Airflow rate Q of secondary airflow SA ₂ 5-15m ³ / Min,
The operating conditions were changed within the range of, and pulverization classification experiment of charcoal cal (limestone) was conducted.
[0055]
As a result, “average particle diameter D of product (fine powder C)” ₅₀ (Μm) and the specific surface area of the product (brain value) (cm ² / G) "is as shown in FIG.
"Product Mill Power Unit (kwh / t) and Product Specific Surface Area (Brain Value)
(Cm ² / G) "is as shown in FIG.
[0056]
In FIG. 7, the horizontal axis represents the specific surface area (brain value) of the product (cm ² / G), the vertical axis is the average particle diameter D of the product ₅₀ (Μm), vertical line X ₁ The conventional grinding limit of 27,000 cm ² The position of / g is shown.
[0057]
I3 to I5 are the primary airflow FA volume (primary airflow) Q ₁ In addition, the air volume (secondary air flow) Q of the secondary air flow SA ₂ Is the case of introducing.
The number after I indicates the rotation speed (unit: 1,000 rpm) of the classification rotor blade. For example, I3 is a rotational speed of 3 × 1,000 rpm.
Air volume Q of mixed swirl flow W ₃ The number after = is the primary airflow rate Q ₁ + Secondary air flow rate Q ₂ Total air volume (m ³ / Min).
Primary air flow Q ₁ Is 35m ³ / Min, for example, Q ₃ = 50 is 50m of mixed swirl flow ³ / Min., Secondary airflow volume Q ₂ Is 15m ³ / Min.
[0058]
E3 to E5 are the primary airflow Q ₁ Only, that is, secondary airflow Q ₂ The number after E is the number of revolutions of the classifier rotor blade (unit: 1,000 rpm). For example, E3 is a rotational speed of 3 × 1,000 rpm.
Primary air flow Q ₁ The number after = is the air volume m ³ / Min, L next to the number indicates that the number is on the air volume line.
For example, Q ₁ = 47 is 47m of primary airflow ³ / Min, Q ₁ = 40L is the primary air flow Q ₁ = 40m ³ / Min. On the line.
[0059]
As is apparent from this figure, the primary air flow rate Q ₁ Only, that is, secondary air flow Q ₂ When the particle size distribution is not introduced, the change range of the particle size distribution is a range surrounded by the curves E3 to E5, that is, a brain value of about 38,000 cm. ² / G ~ 18,000cm ² It is a curve portion in the range of / g.
[0060]
Secondary air flow Q ₂ The change range of the particle size distribution in the case where is introduced is a curve portion from the intersection P3 to P5 on the right side of the range surrounded by the curves I3 to I5, that is, a brain value of about 34,000 cm. ² / G ~ 18,000cm ² It is a curve portion in the range of / g. The intersections P3 to P5 are the curves E3 to E5 and the secondary air flow rate Q when only the primary airflow is introduced. ₂ Is the intersection with the curves I3 to I5.
Comparing each of these curve parts, the secondary air flow rate Q ₂ It can be seen that the particle size distribution can be significantly changed with the same specific surface area.
[0061]
In addition, the average particle diameter D of the product for the fineness of the same specific surface area ₅₀ (Μm) can be changed drastically, so that the particle size distribution width of the product can be changed drastically, and there is also very little intrusion of coarse particles. ₂ Is the result of the introduction of
[0062]
In FIG. 8, the horizontal axis represents the specific surface area of the product (brane value) (cm ² / G), the vertical axis is the product mil power unit (kwh / t), and the vertical line X ₂ Is the position of the pulverization limit of a classifier with poor classification performance (Brain value 20,000 cm ² / G), X ₃ Is the position of the crushing limit when the performance is good (Brain value 28,000 cm ² / G).
[0063]
Vertical line X ₃ The curve I6 on the right side, that is, the direction in which the brane value increases, is when the flakes are discharged from the grinding chamber and returned to the grinding chamber via a circulation circuit, and the curve I7 is the discharge of the flakes from the grinding chamber. After pulverizing
Q ₂ In this case, the coarse powder is mixed into the pulverization chamber.
When the flakes are discharged from the pulverization chamber and crushed and then returned to the pulverization chamber via the circulation circuit, I8 is a value between the curves I6 and I7.
In this figure, the rotation speed of the classifier rotor blade is 5,000 rpm, the dam ring is 20 mm, the primary air flow rate Q ₁ Is 25-45m ³ / Min.
[0064]
As is apparent from this figure, when flakes are not crushed, they are forcedly circulated as they are and returned to the crushing chamber, and when flakes are forcibly crushed, in the case of charcoal cal, the specific surface area (brain value) is 45,000 cm. ² The pulverization limit can be extended to about / g.
[0065]
In addition, after the flakes are crushed, the flakes are returned to the pulverization chamber, or the fine powder is discharged into the secondary air flow rate Q. ₂ And the coarse powder is returned to the crushing chamber to promote fine crushing (in the case of charcoal cal, the brane value is 45,000 cm). ² / G), and a significant increase in the amount of products produced per hour and a reduction in power consumption (kwh / t) can be achieved.
[0066]
In addition, in the said experiment, although the position of the secondary airflow introduction part 60 is an example nearest the lower part of the classifier 11, about the experimental result which changed the position of the secondary airflow introduction part 60 other than this experiment example, it shows. There are no similar results.
That is, even when the secondary air flow introduction part 60 is introduced in the immediate vicinity of the upper part of the pulverization part (crushing chamber) or in the middle position between the upper part of the pulverization chamber and the lower part of the classifier, depending on the position of each introduction part 60. A similar trend is shown.
[0067]
These relationships will be described with reference to FIGS.
FIG. 10 is an illustration of a conventional example. When there are three types of casings between the grinding chamber and the classification chamber, high side H, standard S, and low side L, the degree of fineness OD at the outlet of the primary air flow adjusting nozzle 10 and OD The degree of fineness ID (thin and coarse) at the entrance of the classification chamber is shown by illustrations IL, IS, and IH.
In the degree of fineness OD and ID, the hatched rectangular HS is the primary air flow rate Q. ₁ The solid rectangular WS inside is the primary air flow rate Q. ₁ There are few cases. The longer the length LM of the rectangle is, the rougher it is, and vice versa.
[0068]
As can be seen from this illustration, the primary air flow rate Q ₁ If the air volume is the same, in the case of the low side L, the product with the coarsest degree of fineness is collected with an air classifier.
Therefore, the coarse powder after classification also becomes coarse, and the discharged powder becomes the coarsest when discharged from the pulverization chamber. Therefore, the fineness at the outlet of the nozzle 10 becomes the coarsest, and the classification chamber 5 with the coarsest fineness while turning up. It reaches the entrance and is classified most coarsely by the classifier.
[0069]
The degree of fineness OD at the outlet of the primary air flow adjusting nozzle 10 and the degree of fineness ID at the classification chamber inlet are swirled as the casing becomes finer in the order of standard S and high side H, and reaches the classifier inlet, In the classifier, the illustration shows that the casing is classified finely in the order of standard S and high side H.
[0070]
FIG. 9 is an illustration of the present invention. The pulverized raw material is introduced into the primary airflow FA swirling and rising from the nozzle 10 of the pulverization chamber toward the classification chamber, thereby introducing a secondary airflow SA in the tangential direction in the same direction as the primary airflow to increase the airflow rate. Flow rate Q ₁ And secondary air flow Q ₂ And flow ratio Q ₁ / Q ₂ The method of controlling the particle size distribution of the pulverized product while changing the above is illustrated with an illustration.
[0071]
As understood from this illustration, the same concept as described in FIG. 10 can be applied to this description.
The degree of fineness OD at the outlet of the primary air flow adjustment nozzle 10 is the air flow rate of the primary air flow FA.
Q ₁ When there is a large amount, it becomes rough, and when it is small, there is a relationship that becomes fine.
As described with reference to FIG. 10, when the secondary airflow is introduced from the lower secondary airflow inlet 60 </ b> C, the degree of fineness ID with respect to the classifier inlet becomes coarse and is conveyed to the classifier. Therefore, since the classification conditions of the classifier are constant, the coarse powder after classification also becomes coarse, and the discharged powder becomes coarse when discharged from the pulverization chamber. Further, since the secondary airflow SA is introduced from the lower secondary airflow inlet 60C, the airflow of the ascending swirl flow is further increased, reaches the inlet of the classification chamber 5 with a coarse degree of fineness, and is classified most coarsely by the classifier. Illustrates IL.
[0072]
The degree ID of fineness with respect to the classification chamber inlet becomes finer in order at the positions of the middle secondary air inlet 60B and the upper secondary air inlet 60A, and further the middle and upper secondary air inlets 60B and 60A while turning upward. Since the secondary air flow SA is further introduced, the ascending swirl flow is further strengthened and reaches the classifier inlet with a coarser fineness. In the classifier, the secondary airflow inlet 60B and the upper secondary airflow The illustrations IM and IT show that the classification is performed in the order of the intake port 60A.
[0073]
FIG. 9 also includes the relationship with the illustration of FIG. 10 when the casing is high side H, standard S, and low side L.
That is, it is shown that the object can be achieved only by introducing the secondary air flow SA without changing the height of the casing between the crushing chamber 3 and the classification chamber 5 whenever necessary.
This is the same specific surface area (cm ² ) Average particle size D ₅₀ (Μm), fine particle ratio (%) and coarse particle ratio (%) in the product can be adjusted, indicating that the particle size distribution width can be controlled from broad to sharp.
[0074]
In addition, although the grinding | pulverization raw material used for this experiment is charcoal cal (limestone), it implemented also about the other pulverization raw materials, for example, talc, slag powder, and a silica stone, and obtained the same result.
[0075]
The embodiments of the present invention are not limited to the above, and it is needless to say that modifications can be made as appropriate without departing from the scope of the present invention.
[0076]
【The invention's effect】
The present invention has the following remarkable effects.
(1) A particle size distribution adjusting means is provided between the upper level of the pulverizing roller of the pulverizing chamber and the lower right bottom surface level of the classifying chamber, and introduces a secondary air flow for conveying classification into the conveying swirl flow. Therefore, compared with the conventional example, it is possible to enhance the operability function for easy change of the particle size distribution and control of the change.
(2) Since the flakes discharged from the vertical roller mill are crushed and then returned to the classification chamber or the pulverizing chamber, further pulverization is promoted and the pulverization efficiency is improved in the fine powder region of the roller mill. At the same time, the bulk specific gravity of the material to be crushed and crushed in the crushing chamber can be appropriately reduced according to various crushing materials, compared with the case where flakes are directly returned to the crushing chamber without crushing. It can be increased by making it.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of the present invention.
FIG. 2 is an enlarged view of a main part of FIG.
3 is a cross-sectional view taken along line III-III in FIG.
FIG. 4 is a diagram showing a second embodiment of the present invention.
FIG. 5 is a diagram showing a third embodiment of the present invention.
FIG. 6 is a diagram showing a fourth embodiment of the present invention.
FIG. 7 is a graph showing experimental results.
FIG. 8 is a graph showing experimental results.
FIG. 9 is an illustration showing the relationship between the position of the secondary air flow inlet and the particle size distribution according to the present invention.
FIG. 10 is an illustration showing the relationship between the height of the casing of the conventional example and the particle size distribution.
[Explanation of symbols]
1 outer sealed casing
3 Crushing chamber
5 classification room
8 Crushing roller
11 Air classifier
12 Inside hopper
20 Rotor blade
50 Circulation circuit
60 Secondary airflow introduction part
95 Flakes crusher

Claims (8)

A vertical roller mill crushing chamber provided at the lower part of the outer sealed casing, an air classification chamber provided at the upper part of the outer sealed casing, and a primary air flow for conveying classification is introduced into the outer sealed casing from the crushing chamber. A pulverizing and classifying device comprising a nozzle for forming a swirling flow toward the classification chamber, and a feeding means for supplying a pulverized raw material to the pulverizing chamber;
A crushing and classifying apparatus, comprising a crushing and circulating conveying means for crushing flakes discharged from the vertical roller mill crushing chamber and feeding the flakes to the feeding means. A vertical roller mill crushing chamber provided at the lower part of the outer sealed casing, an air classification chamber provided at the upper part of the outer sealed casing, and a primary air flow for conveying classification is introduced into the outer sealed casing from the crushing chamber. A pulverizing and classifying device comprising a nozzle for forming a swirling flow toward the classification chamber, and a feeding means for supplying a pulverized raw material to the pulverizing chamber;
A particle size distribution adjusting means disposed between an upper end level of the pulverizing roller of the pulverizing chamber and a lower right bottom surface level of the classifying chamber, and introducing a secondary air flow for conveying classification into the conveying swirl flow;
Crushing circulation conveying means for crushing flakes discharged from the vertical roller mill crushing chamber and feeding the flakes to the feeding means;
A pulverizing and classifying device characterized in that is provided. The pulverizing and classifying apparatus according to claim 2, wherein the particle size distribution adjusting means includes a flow rate control device. The particle size distribution adjusting means includes a secondary air flow introduction unit, the crushing circulation conveying unit is connected to the feeding unit via a switching chute, and the switching chute is connected to the secondary air flow introduction unit. pulverizing and classifying apparatus according to claim 2, characterized in that it is connected. A step of supplying pulverized raw material to a vertical roller mill pulverization chamber provided at the lower part of the outer sealed casing, and pulverizing the raw material, the pulverized raw material being formed in the outer sealed casing and going from the pulverization chamber to the air classification chamber A pulverizing and classifying method comprising: a step of carrying the carrier swirl flow; and a step of air classifying the raw material conveyed to the air classification chamber;
After beating flakes discharged from the vertical roller mill grinding chamber, pulverized and classified method and returning to the grinding chamber via a feeding means for supplying a pulverized starting material. A step of supplying a pulverized raw material to a vertical roller mill pulverization chamber provided at a lower portion of the outer sealed casing, and pulverizing the raw material, the pulverized raw material being formed in the outer sealed casing, and from the pulverization chamber to the air classification chamber A pulverizing and classifying method comprising: a step of carrying the carrier on a conveying swirl flow toward the air; and a step of air classifying the raw material conveyed to the air classification chamber;
A secondary air stream for conveying classification is introduced from the tangential direction into the conveying swirl flow located between the upper end level of the pulverizing roller of the pulverizing chamber and the lower right bottom surface level of the classifying chamber, and the vertical roller mill pulverizing chamber After pulverizing the flakes discharged from the pulverized product, the pulverized and classified method is returned to the pulverizing chamber through a feeding means for supplying a pulverized raw material . A step of supplying a pulverized raw material to a vertical roller mill pulverization chamber provided at a lower portion of the outer sealed casing, and pulverizing the raw material, the pulverized raw material being formed in the outer sealed casing, and from the pulverization chamber to the air classification chamber A pulverizing and classifying method comprising: a step of carrying the carrier on a conveying swirl flow toward the air; and a step of air classifying the raw material conveyed to the air classification chamber;
A secondary air stream for conveying classification is introduced from the tangential direction into the conveying swirl flow located between the upper end level of the pulverizing roller of the pulverizing chamber and the lower true bottom surface level of the classification chamber, and the vertical roller mill pulverizing chamber After pulverizing the flakes discharged from the pulverized product , the pulverized product is supplied to the introduction part of the secondary air flow for conveying classification. The pulverization classification method according to claim 6 or 7, wherein the introduction amount of the secondary air flow for conveyance classification is adjustable .

Images